Issue with update_post_thumbnail_cache if using get_posts

[Xendo]

Hello,

I got this:
Warning: Attempt to read property "ID" on int in /wp-includes/post-thumbnail-template.php on line 116

I'm using:

<?php
$posts = get_posts( array( 'fields' => 'ids' ) );

foreach ( $posts as $post_id ) :
        $thumb = get_the_post_thumbnail( $post_id );
endforeach;

The update_post_thumbnail_cache() used in get_the_post_thumbnail() assumes $wp_query->posts always contains an array of $posts objects, while it can be an array of $posts IDs.
To prevent the warning it would be appropriate to check that $post is actually a post object.

The patched code:

<?php
foreach ( $wp_query->posts as $post ) {
        $post = get_post( $post ); // Add this or check if is_integer( $post )
        $id = get_post_thumbnail_id( $post->ID );

Thanks

Kind Regards

[antpb]

Moving this into 6.6 as this is a straightforward problem and solution to validate. Thank you @Xendo for the suggestion!

Fix attempt to read post ID on update_post_thumbnail_cache function as some cases $wp_query->posts return array of post IDs instead of WP_Post object.

Trac ticket: #59521

[oglekler]

It looks like straight forward solution but from my point of view there is still something strange in the functions code itself.

get_the_post_thumbnail() function calls update_post_thumbnail_cache() like this:

if ( in_the_loop() ) {
	update_post_thumbnail_cache();
}

and get_posts() should not set the loop 🤔 and if are getting posts in the loop that has nothing to do with the current post something needs to be done.

Btw, requesting posts one by one that were originally requested only with IDs is incorrect from the beginning because it's raising the amount of requests to the db. Query Monitor is simple tool to check if such things are happening in the code ‎😅 This worth checking from time to time.

We have RC1 today, so, I am moving this ticket to the next milestone for further work.

[LinSoftware]

I attempted to reproduce the PHP warning, but the example code didn't trigger the function update_post_thumbnail_cache to run. Can additional example code be provided?

It looks like update_post_thumbnail_cache only runs in the loop context or in the admin. I agree that performing an individual query for each post is a performance issue.

[peterwilsoncc]

I've added some notes to the pull request about repeating of logic.

[peterwilsoncc]

In 59235:

Media: Account for post ID queries in update_post_thumbnail_cache().

Updates update_post_thumbnail_cache() to account for WP_Query objects that only contain the post ID field rather than the entire post object.

This changes passes the $post value to get_post_thumbnail_id() rather than assuming the presence of the ID property. Additionally, the posts to which the thumbnail is attached are now primed prior to calling the function to avoid numerous unnecessary database queries.

The test WP_Test_REST_Posts_Controller::test_get_items_primes_parent_post_caches() is modified to account for an order of operations change for the priming of post meta caches. The cache is no longer primed in the final call to update_meta_cache() so the tests need to account for the post meta to be primed in any call to the function.

Props antpb, jorbin, khokansardar, linsoftware, mukesh27, oglekler, rajinsharwar, sumitsingh, xendo.
Fixes #59521.

Merged in r59235 / ​https://github.com/WordPress/wordpress-develop/commit/7685041a591ccbc63a55c5bd28e91eca6e260e53

Thank you!